I think the Mermaids scandal is going to be much, much worse than the Kids Company one. Essentially, all that Kids Company did wrong was to waste money. They wasted it in a fairly spectacular fashion, but that's pretty much what it amounted to.
Mermaids is seriously harming children. It's advocating that children and teenagers should be allowed to take drugs that will cause them lifelong damage. It's advocating that they be allowed to have irreversible surgery. They want to allow teenage boys to share changing facilities with teenage girls. To say they are a safeguarding nightmare is an understatement.
When it finally dawns on people what is going on here, and that Mermaids has been supported by establishment bodies such as the police, and been allowed to spread its pernicious ideology in schools, the scandal will be of epic proportions. The only mystery is why it hasn't happened already.